Glaucoma is a disease of the eye that affects millions of people. Glaucoma is associated with an increase in intraocular pressure resulting either from a failure of a drainage system of an eye to adequately remove aqueous humor from an anterior chamber of the eye or overproduction of aqueous humor by a ciliary body in the eye. Build-up of aqueous humor and resulting intraocular pressure may result in irreversible damage to the optic nerve and the retina, which may lead to irreversible retinal damage and blindness.
There are two main types of glaucoma, “open angle” and “closed angle” glaucoma. Open angle glaucoma refers to glaucoma cases in which intraocular pressure increases but an anterior chamber angle (drainage angle) of an eye remains open. A common cause of open angle glaucoma is blockage in the trabecular meshwork, the fluid flow pathways that normally drain aqueous humor from the anterior chamber of the eye. Closed angle glaucoma refers to glaucoma cases in which intraocular pressure increases due to partial or complete closure of the anterior chamber angle. In closed angle glaucoma, swelling or movement of the iris closes the anterior chamber angle and blocks fluid from accessing to the trabecular meshwork, which in turn obstructs outflow of the aqueous humor from the eye.
Generally, glaucoma may be treated by surgical intervention that involves placing a shunt in the eye to result in production of fluid flow pathways between the anterior chamber and various structures of the eye involved in aqueous humor drainage (e.g., Schlemm's canal or the subconjunctival space). Such fluid flow pathways allow for aqueous humor to exit the anterior chamber. Generally, the surgical intervention to implant the shunt involves inserting into the eye a deployment device that holds an intraocular shunt, and deploying the shunt from the device and into the eye. A deployment device holding the shunt enters the eye through a cornea (ab interno approach), and is advanced across the anterior chamber. The deployment device is advanced into the anterior chamber angle and through the sclera until a distal portion of the device is in proximity to a drainage structure of the eye. The shunt is then deployed from the deployment device, producing a conduit between the anterior chamber and various structures of the eye involved in aqueous humor drainage (e.g., Schlemm's canal, the sclera, or the subconjunctival space). See for example, Yu et al. (U.S. Pat. No. 6,544,249 and U.S. patent application number 2008/0108933) and Prywes (U.S. Pat. No. 6,007,511).